1. Field of the Invention
The aircraft loading ramp of the present invention relates generally to adjustable ramps for transferring passengers between a terminal building and an aircraft.
2. Description of the Prior Art
A central problem in the design of loading ramps has been the accommodation of aircraft of varying sizes requiring that the loading ramp be adjustable to accommodate aircraft of different heights. Previous ramp devices attempted to provide a self-leveling mechanism to accommodate the natural tilting of the cab as the tunneled walkway is elevated. Lodgic Canadian Pat. No. 790,811 provides struts pivotally connected to an inner supporting frame and a cab cooperating to provide a parallelogram linkage to maintain the cab level as it is moved. My U.S. Pat. No. 4,110,859 and Sanders U.S. Pat. No. 4,161,049 utilize a parallelogramatic self-leveling mechanism. Such devices are limited in operation because the parallelogramatic linkage will not accommodate a telescoping inner and outer tunnel for horizontal extension of the tunneled walkway since the parallelogramatic operation requires that the distance between the floor and the roof of the tunnel vary as the tunnel is elevated.